Slack, on the Vinegar Plant. 
13 
with the growth of the plant, though under other conditions 
they may be produced by purely chemical means. The cane- 
sugar assimilates one equivalent of water and becomes fruit- 
sugar_, the fruit-sugar is changed into alcohol and carbonic 
acid and the alcohol oxydized, first into aldehyd, and then 
into acetic acid. Professor Miller says, the formation of 
aldelhyd appears always to precede the production of 
vinegar.'^ 
When saccharine matter is fermented into alcohol by 
the agency of yeast-cells, no other microscopic vegetation 
is present in sufficient quantity to affect the result ; but when 
the vinegar fermentation is carried on we find cells closely 
resembling yeast-cells, and also a great number of other cells, 
and these cells, together with the gelatinous material to 
which they give rise, and in which they are imbedded, appear 
to be oxydizing agents by which the alcohol is further trans- 
formed. 
Since I described the bacterium bodies which the vinegar 
plant contains, in the ' Intellectual Observer/ vol. iv, p. 238, 
I have made further experiments with vinegar plants, and 
now venture to claim tlie attention of the Society to some 
of the facts ascertained. I took a large vinegar plant out 
of a saccharine solution in which it was growing, and left 
it on a plate in a warm room. It soon came to the con- 
dition of a slightly moist piece of leather, and was allowed 
to remain in that state for some time. In dry weather it 
lost a little moisture, and on damp days took in a fresh 
supply. It was finally placed in a large porcelain dish, filled 
with sugar and water, and soon yielded a great crop of blue, 
green, and yellow mould, with beautiful strings and tufts 
of spores. No vinegar appeared, though the sugar disap- 
peared, and after the process had gone on for some months, 
I obtained no alcohol on distilling a portion of the liquid. 
A microscopic examination showed that the same struc- 
tures were present in this vinegar plant as it had contained 
when it was engaged in acetefying the solution in which 
it originally grew, and there could have been no general 
death among them, since they produced magnificent crops 
of mould. In the original state of the plant, the diff'erent 
kinds of cells seemed to form a co-operative colony, and the 
growth of this colonial system was correlative with the pro- 
duction of the vinegar. After the plant had been removed 
from the solution and exposed freely for a considerable 
time to the air, it seemed to die as a colony, though par- 
ticular cells gave birth to innumerable spots of mould. The 
plant did not, in this instance, decompose or go to pieces j 
